Self contained mobile inspection system and method

ABSTRACT

The inspection methods and systems of the present invention are mobile, rapidly deployable, and capable of scanning a wide variety of receptacles cost-effectively and accurately on uneven surfaces. The present invention is directed toward a portable inspection system for generating an image representation of target objects using a radiation source, comprising a mobile vehicle, a detector array physically attached to a movable boom having a proximal end and a distal end. The proximal end is physically attached to the vehicle. The invention also comprises at least one source of radiation. The radiation source is fixedly attached to the distal end of the boom, wherein the image is generated by introducing the target objects in between the radiation source and the detector array, exposing the objects to radiation, and detecting radiation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/753,976, Apr. 5, 2010 now U.S. Pat. No. 7,995,705, which isa continuation of U.S. patent application Ser. No. 12/349,534, Jan. 7,2009 now U.S. Pat. No. 7,720,195, which is a continuation of U.S. patentapplication Ser. No. 10/939,986, filed on Sep. 13, 2004, now issued asU.S. Pat. No. 7,486,768, which is a continuation-in-part of U.S. patentapplication Ser. No. 10/915,687, filed on Aug. 9, 2004, now U.S. Pat.No. 7,322,745, which is a continuation-in-part of U.S. patentapplication Ser. No. 10/201,543, filed on Jul. 23, 2002, now U.S. Pat.No. 6,843,599, which claims priority to U.S. Provisional Application No.60/502,498, filed on Sep. 12, 2003.

FIELD OF THE INVENTION

The present invention relates generally to a self-contained mobileinspection system and method and, more specifically, to improved methodsand systems for detecting materials concealed within a wide variety ofreceptacles and/or cargo containers. In particular, the presentinvention is directed towards improved methods and system components forreducing the overall weight and dimensions of the scanning system,eliminating the need for continual system alignment, allowing for a moreprecise radiation source beam via collimation techniques, and enablingbetter visibility of the floor level of the object or vehicle underinspection.

BACKGROUND OF THE INVENTION

X-ray systems are used for medical, industrial and security inspectionpurposes because they can cost-effectively generate images of internalspaces not visible to the human eye. Materials exposed to X-rayradiation absorb differing amounts of X-ray radiation and, therefore,attenuate an X-ray beam to varying degrees, resulting in a transmittedlevel of radiation that is characteristic of the material. Theattenuated radiation can be used to generate a useful depiction of thecontents of the irradiated object. A typical single energy X-rayconfiguration used in security inspection equipment may have afan-shaped or scanning X-ray beam that is transmitted through the objectinspected. The absorption of X-rays is measured by detectors after thebeam has passed through the object and an image is produced of itscontents and presented to an operator.

Trade fraud, smuggling and terrorism have increased the need for suchnon-intrusive inspection systems in applications ranging from curbsideinspection of parked vehicles to scanning in congested or high-trafficports because transportation systems, which efficiently provide for themovement of commodities across borders, also provide opportunities forthe inclusion of contraband items such as weapons, explosives, illicitdrugs and precious metals. The term port, while generally accepted asreferring to a seaport, also applies to a land border crossing or anyport of entry.

With an increase in global commerce, port authorities require additionalsea berths and associated container storage space. Additional spacerequirements are typically met by the introduction of higher containerstacks, an expansion of ports along the coastline or by moving inland.However, these scenarios are not typically feasible. Space is generallyin substantial demand and short supply. Existing ports operate under aroutine that is not easily modified without causing disruption to theentire infrastructure of the port. The introduction of new procedures ortechnologies often requires a substantial change in existing portoperating procedures in order to contribute to the port's throughput,efficiency and operability.

With limited space and a need to expand, finding suitable space toaccommodate additional inspection facilities along the normal processroute remains difficult. Additionally, selected locations are notnecessarily permanent enough for port operators to commit to. Moreover,systems incorporating high-energy X-ray sources, or linear accelerators(LINAC), require either a major investment in shielding material(generally in the form of concrete formations or buildings) or the useof exclusion zones (dead space) around the building itself. In eithercase the building footprint is significant depending upon the size ofcargo containers to be inspected.

A mobile inspection system offers an appropriate solution to the needfor flexible, enhanced inspection capabilities. Because the system isrelocatable and investing in a permanent building in which toaccommodate the equipment is obviated, site allocation becomes less ofan issue and introducing such a system becomes less disruptive. Also, amobile X-ray system provides operators, via higher throughput, with theability to inspect a larger array of cargo, shipments, vehicles, andother containers.

An example of a mobile X-ray inspection system is provided in U.S. Pat.No. 5,692,028 assigned to Heimann Systems. The '028 patent discloses anX-ray examining system comprising a mobile vehicle and an X-rayexamining apparatus for ascertaining contents of an object, saidapparatus including a supporting structure mounted on the mobilevehicle; said supporting structure being portal-shaped for surroundingthe object on top and on opposite sides thereof during X-rayexamination; said supporting structure including (i) a generallyvertical column mounted on said vehicle and rotatable relative to saidvehicle about a generally vertical axis; said column having an upperend; (ii) a generally horizontal beam having opposite first and secondend portions; said beam being attached to said upper end at said firstend portion for rotation with said column as a unit for assuming aninoperative position vertically above said mobile vehicle and anoperative position in which said beam extends laterally from saidvehicle; and (iii) an arm pivotally attached to said second end portionof said beam for assuming an inoperative position in which said armextends parallel to said beam and an operative position in which saidarm extends generally vertically downwardly from said beam; an X-raysource for generating a fan-shaped X-ray beam; said X-ray source beingcarried by said vehicle; and an X-ray detector mounted on saidsupporting structure; said X-ray examining system being adapted totravel along the object to be examined while irradiating the object anddetecting the X-rays after passage thereof through the object.

U.S. Pat. No. 5,764,683 assigned to AS&E discloses a device forinspecting a cargo container, the device comprising: a bed moveablealong a first direction having a horizontal component; a source ofpenetrating radiation, mounted on the bed, for providing a beam; amotorized drive for moving the bed in the first direction; at least onescatter detector mounted on the bed, the at least one scatter detectorhaving a signal output; and a transmission detector for detectionpenetrating radiation transmitted through the cargo container such thatthe beam is caused to traverse the cargo container as the bed is movedand the at least one scatter detector and the transmission detector eachprovide a signal for characterizing the cargo container and any contentsof the cargo container.

U.S. Pat. No. 6,252,929 assigned to AS&E claims a device for inspectinga cargo container with penetrating radiation, the device comprising: abed that is reversibly moveable along a direction having a horizontalcomponent; a source of penetrating radiation, mounted on the bed forproviding a beam having a central axis, the central axis beingpredominantly horizontal; a motorized drive for moving the bed in thefirst direction; at least one scatter detector mounted on the bed, eachscatter detector having a signal output; so that, as the bed is movedforward and backward along the direction, the beam is caused to traversethe cargo container as the bed is moved and each scatter detectorprovides a signal for characterizing the cargo container and anycontents of the cargo container.

U.S. Pat. No. 6,292,533, also assigned to AS&E, claims a system forinspecting a large object with penetrating radiation during motion ofthe system in a scan direction, the system comprising: a vehicle havingwheels and an engine for propelling the vehicle on highways; a boomhaving a proximal end rotatable about a point on the vehicle and adistal end, the boom deployed transversely to the scan direction forstraddling the object during operation of the system; a source ofpenetrating radiation coupled to the vehicle for providing a beam sothat the beam is caused to irradiate a first side of the object as thevehicle is moved in the scan direction; and at least one detectorcoupled to the vehicle on a side of the object opposing the first side,the at least one detector having a signal output, the at least onedetector providing a signal for imaging the object.

U.S. Pat. No. 5,903,623, assigned to AS&E, claims a device, forinspecting a large object with penetrating radiation, the devicecomprising: a self-propelled vehicle capable of on-road travel; a sourceof penetrating radiation, mounted on the vehicle, for providing a beamof penetrating radiation; a beam stop for absorbing the beam ofpenetrating radiation after traversal of the object; and at least onedetector coupled to the vehicle, the at least one detector having asignal output so that the beam is caused to traverse the object in afirst direction as the vehicle is moved and the signal outputcharacterizes the object.

In addition to the features described above, conventional relocatableinspection systems generally comprise at least two booms, wherein oneboom will contain a plurality of detectors and the other boom willcontain at least one X-ray source. The detectors and X-ray source workin unison to scan the cargo on the moving vehicle. In conventionalsingle boom relocatable inspection systems, the X-ray source is locatedon a truck or flatbed and the detectors on a boom structure extendingoutward from the truck.

The aforementioned prior art patents are characterized bymoving-scan-engine systems wherein the source-detector system moves withrespect to a stationary object to be inspected. Also, the detectors andthe source of radiation are either mounted on a moveable bed, boom or avehicle such that they are integrally bound with the vehicle. Thislimits the flexibility of dismantling the entire system for optimumportability and adjustable deployment to accommodate a wide array ofdifferent sized cargo, shipments, vehicles, and other containers. As aresult these systems can be complicated to deploy and pose severaldisadvantages and constraints.

For example, in a moving-scan-engine system the movement of the sourceand detector, relative to a stationary object, may cause lateral twistand lift and fall of the detector or source, due to movement of thescanner over uneven ground, inducing distortions in the scanned imagesand faster wear and tear of the scanner system. Systems where the weightof the detector or source is held on a boom require high structuralstrength for the boom in order to have the boom stable for imagingprocess, thereby adding more weight into the system. Such systems thatrequire a detector-mounted boom to unfold during deployment may cause anunstable shift of the center of gravity of the system off the base,causing the system to tip over. Further, in the case ofmoving-scan-engine systems using a “swing arm” boom approach, the driverdriving the scanner truck is unable to gauge the possibility of hittingthe detector box, mounted on a boom, with a vehicle under inspection(VUI), as the detector box is on the other side of the VUI duringscanning and not visible to the driver.

Additionally, with moving-scan-engine systems, the truck supporting thescanner system is always required to move the full weight of the scannerregardless of the size and load of the VUI, putting greater strain onthe scanning system. Further, because of the integrated nature of priorart systems, swapping detector and radiation systems between scanningsystems is not feasible. In terms of throughput, prior art systems needadditional operational systems that greatly multiply the cost ofoperation to increase the number of VUI to be handled. Alsodisadvantageous in conventional systems is that they suffer from a lackof rigidity, are difficult to implement, and/or have smaller fields ofvision.

Accordingly, there is need for improved inspection methods and systemsbuilt into a fully self-contained, over-the-road-legal vehicle that canbe brought to a site and rapidly deployed for inspection. The improvedmethod and system can, therefore, service multiple inspection sites andset up surprise inspections to thwart contraband traffickers whotypically divert smuggling operations from border crossings that havetough interdiction measures to softer crossings with lesser inspectioncapabilities. Moreover, there is an additional need for methods andsystems that require minimal footprint to perform inspection and thatuse a sufficient range of radiation energy spectrum to encompass safeand effective scanning of light commercial vehicles as well assubstantially loaded 20-foot or 40-foot ISO cargo containers. It isimportant that such scanning is performed without comprising theintegrity of the cargo and should ideally be readily deployable in avariety of environments ranging from airports to ports of entry where asingle-sided inspection mode needs to be used due to congestedenvironments. Such needs are addressed in co-pending U.S. patentapplication Ser. No. 10/201,543, entitled “Self-Contained PortableInspection System and Method”, which is herein incorporated by referencein its entirety.

Improved methods and systems are additionally needed to keep therelative position between the radiation source and detector fixed toavoid distortion in images caused by the movement of scanner and/ordetectors over uneven ground or due to unstable structures. In addition,there is a need for improved methods and systems that can providecomprehensive cargo scanning in portable and stationary settings.Specifically, methods and systems are needed in which a single boom isemployed for generating quality images for inspection. Further, thesystem should be mounted on a relocatable vehicle, capable of receivingand deploying the boom.

What is also needed is a single boom cargo scanning system that enablesquick and easy deployment, rigidity and tight alignment of the radiationsource and detectors, and a narrow collimated radiation beam, thusallowing for a smaller exclusion zone. In addition, what is needed is anoptimal scanning system design that allows for the radiation source tobe closer to the Object under Inspection (“OUI”), thereby allowing forhigher penetration capability and complete scanning of the targetvehicle without corner cutoff. Such needs are addressed in co-pendingU.S. patent application, entitled “Single Boom Cargo Scanning System”and filed on Aug. 8, 2004, which is herein incorporated by reference inits entirety.

Additionally, what is needed is an improved method and system forreducing the overall weight and dimensions of the scanning system. Suchimproved methods and systems would allow for lowering the overall centerof gravity of the system by reducing the top-heaviness of the system.What is also needed is a system that eliminates the need for continualsystem alignment. In addition, a system that allows for a more preciseradiation source beam via unique collimation techniques is needed. Whatis also needed is a system configured for dual-sided operation, in whichthe radiation and detector source can be deployed on either side of thevehicle upon which it is mounted allowing for greater flexibility inoperation. And finally, what is needed is a system that enables bettervisibility of the floor level of the object or vehicle under inspection.

SUMMARY OF THE INVENTION

The inspection methods and systems of the present invention are mobile,rapidly deployable, and capable of scanning a wide variety ofreceptacles cost-effectively and accurately on uneven surfaces. In afirst embodiment, a self-contained inspection system comprises aninspection module that, in a preferred embodiment, is in the form of amobile trailer capable of being towed and transported to its intendedoperating site with the help of a tug-vehicle.

In a second embodiment, the present invention is directed toward aportable inspection system for generating an image representation oftarget objects using a radiation source, comprising a mobile vehicle; adetector array physically attached to a movable boom having a proximalend and a distal end, wherein the proximal end is physically attached tothe vehicle; and at least one source of radiation wherein the radiationsource is fixedly attached to the distal end of the boom, wherein theimage is generated by introducing the target objects in between theradiation source and the detector array, exposing the objects toradiation, and detecting radiation. Preferably, the system furthercomprising a hydraulic system located in the vehicle to move the boom.

In a third embodiment, the present invention is directed toward aportable inspection system for generating an image representation oftarget objects using a radiation source, comprising a mobile vehicle, adetector array physically attached to a movable boom having a proximalend and a distal end wherein the proximal end is physically attached tosaid vehicle; and at least one source of radiation wherein the radiationsource is located on a rotatable platform fixedly attached to theproximal end of said boom, wherein the image is generated by introducingthe target objects in between the radiation source and the detectorarray, exposing the objects to radiation, and detecting radiation; and apost collimator integrally connected between the radiation source andthe proximal end of the movable boom.

Optionally, the present invention further comprises a hydraulic or cablesystem located in the vehicle to move the boom. The present inventionfurther comprises at least one sensor to determine when a target objectis positioned between the radiation source and the detector array. Thesensor, upon being activated by the movement of a target object,transmits a signal to activate said radiation source.

Optionally, the boom has a main body physically attached to the vehicle,an outer arm physically attached to the main body, and a telescopic armphysically attached to the outer arm. The boom has a first configurationand a second configuration. In a first configuration, the outer arm andtelescopic arm are positioned in substantial parallel alignment with thevehicle. In a second configuration, the outer arm and telescopic arm arepositioned to align in a range from 90 degrees to 100 degrees with thevehicle.

The radiation source is preferably aligned with the detector system. Theradiation source is aligned with the detector system using opticaltriangulation techniques. The detectors are angled at substantially 90degrees relative to a focal point of said radiation source.

In another embodiment of the present invention, a method for inspectingobjects using a portable inspection system that generates an imagerepresentation of a target object using a radiation source, comprisingthe steps of transporting a detector array and at least one source ofradiation to an operation site using a vehicle, wherein the detectorarray is physically attached to a movable boom having a proximal end anda distal end, wherein the proximal end is physically attached to thevehicle, and wherein the radiation source is fixedly attached to arotatable platform located on the proximal end of the boom; creating adetection region by moving the boom into a substantially perpendicularposition relative to said vehicle; activating the radiation source;moving the vehicle passed the target object such that the target objectpasses through said detection region; exposing the target object toradiation emitted from the radiation source wherein the exposing stepresults in secondary radiation; and detecting secondary radiation by thedetector array. Preferably, the motion of the vehicle is substantiallyconstant at a plurality of speed settings. The vehicle comprises ahydraulic or cable system to move the boom. Optionally, the presentinvention further comprises the step of detecting when the target objectenters the detection region.

The aforementioned and other embodiments of the present invention shallbe described in greater depth in the drawings and detailed descriptionprovided below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will beappreciated, as they become better understood by reference to thefollowing Detailed Description when considered in connection with theaccompanying drawings, wherein:

FIG. 1 provides a perspective view of one embodiment of an exemplaryself-contained inspection system of the present invention;

FIG. 2 depicts one embodiment of a hydraulic lift mounted on atug-vehicle and the unloading of a radiation source;

FIG. 3 is a side elevation view of one embodiment of the portableinspection trailer;

FIG. 4 is a side elevation view of one embodiment of the presentinvention in operational mode;

FIG. 5 is a side view of a second embodiment of the present system;

FIG. 6 is a second embodiment of an inspection trailer;

FIG. 7 is one embodiment of an inspection trailer, depicting the use ofa hydraulic system;

FIG. 8 is top plan view of a second embodiment of the present inventionduring operation;

FIG. 9 a is a schematic view of an exemplary hydraulic system used forautomatically unfolding the detector panels;

FIG. 9 b is a second view of an exemplary hydraulic system used forautomatically unfolding the detector panels;

FIG. 10 is a flowchart of one exemplary process for setting-up thesystem of the present invention;

FIG. 11 is a flowchart of one exemplary process for deploying thedetector system;

FIG. 12 is a view of an exemplary radiation source box;

FIG. 13 is a representation of an exemplary embodiment of the integratedsingle boom cargo scanning system of the present invention;

FIG. 14 is a side view illustration of one embodiment of the vehicle ofthe present invention in a “stowed” position;

FIG. 15 is a top view illustration of one embodiment of the vehicle ofthe present invention in a “stowed” and relocatable position;

FIG. 16 is a side perspective view of the single boom cargo scanningtruck of the present invention in a preferred embodiment;

FIG. 17 depicts the top view of the single boom cargo scanning system ofthe present invention, in a deployed position;

FIG. 18 depicts an exemplary movement of the telescopic arm of thesingle boom cargo scanning truck of the present invention;

FIG. 19 depicts a second exemplary movement of the telescopic arm of thesingle boom cargo scanning truck of the present invention;

FIG. 20 is a rear view illustration of the single boom cargo scanningsystem of the present invention, in a preferred usage;

FIG. 21 depicts the rotating collimation wheel employed in the scanningsystem of the present invention;

FIG. 22 illustrates a preferred embodiment of the detector array asemployed in the single boom cargo scanning system of the presentinvention;

FIG. 23 is a detailed illustration of one embodiment of the detectorsemployed in the detector array shown in FIG. 10;

FIG. 24 is a detailed illustration of another embodiment of thedetectors employed in the detector array shown in FIG. 10, where thedetectors are arranged in a dual row;

FIG. 25 is a block diagram of an exemplary display and processing unitof the single boom cargo scanning system of the present invention;

FIG. 26 is a flowchart depicting the operational steps of the singleboom cargo scanning system of the present invention upon execution of animage generation program;

FIG. 27 is a rear perspective view of a third embodiment of an exemplaryself-contained inspection system of the present invention;

FIG. 28 depicts a top planar view of an exemplary counterbalancelocation and pre-collimation slot built into the boom tower of thepreferred third embodiment of the present invention;

FIG. 29 is a schematic representation of a preferred stowed position ofthe self-contained inspection system of the present invention in whichthe vertical boom element is in a stowed position at of degrees;

FIG. 30 is a schematic representation of a conventional stowed positionof a self-contained inspection system, by way of reference, in which thevertical boom element is in a stowed position of 90 degrees;

FIG. 31 depicts one exemplary use of the self-contained inspectionsystem of the present invention, scanning an object under inspection;and

FIG. 32 is a schematic representation of one exemplary use of theself-contained inspection system of the present invention, scanning anobject under inspection, as shown in FIG. 31.

DETAILED DESCRIPTION OF THE INVENTION

The inspection methods and systems of the present invention are mobile,rapidly deployable, and capable of scanning a wide variety ofreceptacles cost-effectively and accurately, with rigidity, ease of use,and a wider field of vision. Reference will now be made in detail tospecific embodiments of the invention. While the invention will bedescribed in conjunction with specific embodiments, it is not intendedto limit the invention to one embodiment.

In a first embodiment, FIG. 1 shows a perspective view of an exemplaryself-contained inspection system 100. The system 100 comprises of aninspection module 15 that, in a preferred embodiment, is in the form ofa mobile trailer capable of being towed and transported to its intendedoperating site with the help of a tug-vehicle 10. While the presentinvention is depicted as a tug vehicle 10 connected to a trailer 15, oneof ordinary skill in the art would appreciate that the vehicular portionof the system and inspection module portion of the system could beintegrated into a single mobile structure, for example, a single truckunit. The preferred embodiment uses a tug vehicle independent from theinspection module because, as later discussed, it adds greaterflexibility in how the system is used. In another embodiment, theoperator trailer, unit 15, could be a separate vehicle by itself. Thus,the term “trailer” refers to any type of operator driven orself-propelled vehicle or mobile unit, including but not limited to, atruck in which the system and inspection module are integrally connectedto the vehicular portion, a mobile rig/tractor trailer combination inwhich a platform is towed by a tug-vehicle, or a towed platform.

The tug-vehicle 10 can serve as a support and carrier structure for atleast one source of electromagnetic radiation 11; hydraulic lift system12, such as the Hiab lifting cranes along with suitable jigs andfixtures or any other lifting mechanism known in the art, to load andunload the at least one source 11; and a possible radiation shield plate13 on the back of the driver cabin of tug-vehicle 10, to protect thedriver from first order scatter radiation. The inspection trailer 15 ishitched to the tug-vehicle 10 using a suitable tow or hitch mechanism 5such as class I through V frame-mounted hitches; fifth wheel andgooseneck hitches mounted on the bed of a pick-up; a simplepintle-hitch; branded hitches such as Reese, Pull-rite and Hensley orany other means known to one of ordinary skill in the art. The class ofthe hitch indicates the amount of trailer load that it can handle. Forexample, a class I hitch is rated for a trailer load of about 2000pounds whereas a class V hitch is rated for loads greater than 10,000pounds. A typical manually-releasable tow-bar mechanism, disclosed inU.S. Pat. No. 5,727,806 titled “Utility Tow Bar” and assigned to ReeseProducts Inc., comprises a coupler assembly including a hitch ballreceiving socket and cooperating lock. This facilitates selectiveconnection of a tow-bar to the hitch ball of a trailer hitch receivercarried by a towing vehicle. Alternatively, automatic hitches may alsobe used for quick coupling and detaching of the tow truck and trailerwithout manual intervention or attendance.

Referring back to FIG. 1, the inspection or scanning module 15 iscustom-built as a mobile trailer can provide support for a plurality ofdetector arrays 16 and a boom 17 to deploy a power cable to at least onesource of radiation during operation. The trailer 15 also houses anoperator/analyst cabin including computer and imaging equipment alongwith associated power supplies, air conditioning and power generatingequipment in accordance with the understanding of a person of ordinaryskill in the art of X-ray generation. In high energy/high performancesystem, the trailer containing the detector array 16 and boom 17 may bein a different unit from the trailer housing the operator inspectionroom 15. This will allow the operator to avoid being in a high radiationarea and reduce the amount of shielding required for his protection. Inpreferred embodiment, the trailer 15 may additionally include aplurality of leveling or support feet 18, 19 to enable stabilizedimaging when in stationary use.

In order to use the system 100, the inspection trailer 15 is towed tothe inspection site by the tug-vehicle 10. After positioning theinspection trailer 15, the tug-vehicle 10 is detached and movedsubstantially parallel to the trailer 15 and towards the side carryingthe detector system 16. Here, the radiation source box 11 is shifted outof the tug-vehicle 10 and lowered down to the ground by a hydrauliccrane 12 mounted on the tug-vehicle 10. Thus, the source box 11 isplaced laterally opposite to the detector system 16 at a distance thatis suitable to allow an OUI to pass between the source 11 and detector16 during the scanning process. An OUI could be any type of object,including cars, trucks, vans, mobile pallets with cargo, or any othertype of moveable object. During the scanning process, the tug-vehicle10, after lowering down the source 11, is maneuvered to attach to theOUI and tow the OUI through the radiation scan beam. As the OUI is towedthrough the radiation beam, an image of the OUI is produced on theinspection computers housed within the trailer 15 showing theradiation-induced images of the articles and objects contained withinthe OUI.

Referring to FIG. 2, a rear elevation view of a preferred embodiment ofthe tug-vehicle 10, depicting the unloading of source of radiation 11using a lifting mechanism 12 is shown. As previously mentioned, in apreferred use of the system, the tug vehicle is separated from thetrailer and driven to an area where the source is to be positioned,preferably largely parallel to the trailer and separated from thetrailer by sufficient space to allow an OUI, such as a vehicle orcontainer, to pass.

To allow for the safe and rapid deployment of the radiation source 11, apreferred embodiment uses stabilizing feet 14 to increase the base ofthe tug vehicle 10 and off load the stress from the wheels, as thesource 11 is lifted off the tug-vehicle 10 using a suitable hydrauliclift 12 and brought down from the side for deployment. The radiationsource 11 may be put into position using any means known to one ofordinary skill in the art, such as a wheeled platform. The hydrauliclift 12 puts the source box 11 on a wheeled platform so that the sourcecan now be tugged and can be angularly rotated into a suitable position.

The source of radiation 11 includes radio-isotopic source, an X-ray tubeor any other source known in the art capable of producing beam flux andenergy sufficiently high to direct a beam to traverse the space throughan OUI to detectors at the other side. The choice of source type and itsintensity and energy depends upon the sensitivity of the detectors, theradiographic density of the cargo in the space between the source anddetectors, radiation safety considerations, and operationalrequirements, such as the inspection speed. One of ordinary skill in theart would appreciate how to select a radiation source type, dependingupon his or her inspection requirements. In one embodiment, where theOUI is a large sized container or car that highly attenuates the X-raybeam, the radiation could be from an X-ray tube operating at a voltagein substantial excess of 200 keV, and may operate in a region ofapproximately 4.5 MeV.

A further possibility for examining an OUI can be achieved by drivingthe radiation source 11 with respectively different radiation energiesor by using two detector systems, having varying sensitivities todiffering radiation energies. By comparing at least two congruentradiation images that were obtained with respectively differentradiation energies, it could be possible to discriminate articles havinglow and high ordering number. Organic materials, such as drugs andexplosives, can thus be better distinguished from other materials, forexample metals (weapons).

While the tug vehicle has been moved, with the radiation source, to aposition for the deployment of the radiation source, the inspectiontrailer is also being deployed. Referring now to FIG. 3 a side elevationview of the portable inspection trailer 15 is shown incorporating a boom17 and a plurality of detectors 16 folded to the side of the trailer 15.The detectors 16 are preferably in a formation that, when folded orstored, permits the trailer 15 to safely travel on public roadways.Additionally, the detectors 16 are preferably integrally formed toenable for stable, yet rapid deployment. The detectors may also belinear arrays that extend substantially parallel to the base of thetrailer and, when deployed, extend substantially orthogonal to the baseof the trailer.

In one embodiment, as shown in FIG. 4, the detectors comprise threesections 16 a, 16 b and 16 c that are capable of being folded, asearlier seen in FIG. 3, such that, when in a storage position, thedetectors recess into the side of the inspection trailer 15. By formingdetectors such that they can fold in a storage position, it is possibleto produce a compact trailer 15 that can safely, and legally, travelroadways. When unfolded during operation, the detectors 16 a, b and c,may assume a linear or an arched shape. In one embodiment the detectorsassume an approximate “C” shape, as seen in FIG. 4. The preferred “C”shape allows for a shorter total height of detectors in folded position,minimizes alignment problem because top and bottom sections 16 a, 16 care almost in the same line, provides a relatively smaller dose to alldetectors and are less prone to damage by the effective overall heightof the trailer 15. As shown, the detector sections 16 a, 16 b, and 16 care in alignment with a radiation source 11 that is powered through apower cable 25 attached to a boom 17. Within the area defined betweenthe detector sections 16 a, b, and c and the radiation source 11 is anOUI 20.

In order to facilitate push-button deployment and the dispensing away ofassembling tools or skill, the action of folding or unfolding of thedetectors 16 a, 16 b and 16 c is managed by a suitable hydraulic systemknown to a person of ordinary skill in the art.

FIGS. 6 and 7 show one embodiment of the inspection trailer 15,depicting the use of a typical hydraulic system 22 for deploying anexemplary array of linear-shaped detectors 21. During operation, thehydraulic mechanism 22, pushes the detectors 21 in a substantiallyvertical position while the stabilizing feet 25 and 26 are deployeddownwards so that the trailer 15 now partially rests on them instead ofjust on the wheels, thereby minimizing movement and providing stabilityto the trailer 15 during the scanning operation. A boom 23, is alsoshown in a rest position lying on the top of the trailer 20, and pivotedat one end around a vertical axis 24, such that the boom 23 can rise androtate orthogonally relative to the trailer 15 during deployment.

In one embodiment, as shown in FIG. 4, the detectors 16 remain folded toa side of the trailer 15 in an approximately vertical position so thatthe associated hydraulic mechanism is only used to unfold the foldedsections of the detector system 16. FIGS. 9 a and 9 b show an exemplaryhydraulic system 900 used to unfold the top detector panel 916 a. Thehydraulic system 900 comprises a reversible electrical motor 907 todrive a hydraulic pump 906 that in turn provides hydraulic fluid underpressure to a double acting hydraulic actuator 905 attached to trailer915. When the hydraulic actuator 905 is required to unfold the detector916 a, pressurized hydraulic fluid is pumped into chamber A, engagingpiston 908 to move slider ball 909 that in turn unfolds the detector 916a. Once the detector 916 a is unfolded through an acceptable angle 910the detector 916 a is securely latched in position using a mechanicallatch 920 such as a simple hook and peg system or any other latchingarrangement known to one of ordinary skill in the art. A similararrangement can be used to deploy the lower detector panel.

The detectors 16 may be formed by a stack of crystals that generateanalog signals when X-rays impinge upon them, with the signal strengthproportional to the amount of beam attenuation in the OUI. In oneembodiment, the X-ray beam detector arrangement consists of a lineararray of solid-state detectors of the crystal-diode type. A typicalarrangement uses cadmium tungstate scintillating crystals to absorb theX-rays transmitted through the OUI and to convert the absorbed X-raysinto photons of visible light. Crystals such as bismuth germinate,sodium iodide or other suitable crystals may be alternatively used asknown to a person of ordinary skill in the art. The crystals can bedirectly coupled to a suitable detector, such as a photodiode orphoto-multiplier. The detector photodiodes could be linearly arranged,which through unity-gain devices, provide advantages overphoto-multipliers in terms of operating range, linearity anddetector-to-detector matching. In another embodiment, an area detectoris used as an alternative to linear array detectors. Such an areadetector could be a scintillating strip, such as cesium iodide or othermaterials known in the art, viewed by a suitable camera or opticallycoupled to a charge-coupled device (CCD).

FIG. 8 shows a plan view of the inspection trailer 15, associated imageprocessing and control system 40 and an arrangement of detector system16 as seen from the top. As shown, the plane of the detector system 16represented by axis 35, is kept slightly skewed from the respective sideof the trailer 15 by an angle 36, such as 10°, so that the angle betweenthe trailer 15 and the path of the radiation beam 30 is substantially inexcess of 90°. At angles of about 90° and above, relative to scatterlocation and beam path 30, the magnitude of first order scatterradiation is quite low. In the present system, when radiation is firstemitted, the most likely scatter source is the detector system 16.Therefore the resulting relative angular position, between the axis 35and beam path 30 due to the skew angle of the detector plane 35 from thetrailer 15, helps in protecting driver 37 of the tug-vehicle 20 fromradiations scattered by the detector system 16.

The X-ray image processing and control system 40, in an exemplaryembodiment, comprises a computer and storage systems which records thedetector snapshots and software to merge them together to form an X-rayimage of the vehicle 20 which may further be plotted on a screen or onother media. The X-ray image is viewed or automatically analyzed by OUIacquisition system such as a CRT or monitor that displays the X-rayimage of the vehicle 20 to an operator/analyst. Alternatively, the OUIacquisition systems may be a database of X-ray images of desiredtargets, such as automobiles, bricks or other shapes that can becompared with features in the image. As a result of this imaging, onlyarticles that were not contained in the reference image of the containeror vehicle 20 are selectively displayed to an operator/analyst. Thismakes it easier to locate articles that do not correspond to a referencecondition of the container or vehicle 21, and then to conduct a physicalinspection of those articles. Also, for high-resolution applications,the electronics used to read out the detector signals may typicallyfeature auto-zeroed, double-correlated sampling to achieve ultra-stablezero drift and low-offset-noise data acquisition. Automatic gain rangingmay be used to accommodate the wide attenuation ranges that can beencountered with large containers and vehicles.

Referring now to FIG. 10, during deployment the inspection trailer istransported 1005 to the operation site and towed 1010 in position by thetug-vehicle. The trailer is advantageously positioned proximate to acargo loading area so that the laden cargo containers can pass throughthe source-trailer system without disrupting port activities. One suchpreferable place for positioning the trailer could be an exit point of aport. Another aspect that may influence the decision of positioning thetrailer could be the availability of a large enough area, called the“exclusion zone”, around the scanner system. The exclusion zone is anarea around the scanner in which general public are not authorized toenter due to the possibility of their getting exposed to doses ofradiations scattered during the scanning process. The exclusion area isdependent upon the magnitude of current setting the intensity of theradiation source.

After positioning the trailer suitably, the tug-vehicle is preferablydetached 1015 from the trailer. Next the tug vehicle is moved 1020 to anarea proximate to and preferably parallel from the inspection trailer inorder to unload and position the source of radiation. The source ofradiation is then pulled 1025, or lowered, out of the tug-vehicle, usinga hydraulic lift, and lowered down to the ground to be deployedlaterally opposite to the side of the trailer supporting the detectors.The boom is also rotated 1030 substantially orthogonally from its restposition in order to deploy 1030 control cable to provide power andcontrol signals to the source. The electrical power generator, housed inthe trailer, is now turned on 1035 to provide power to the electricaldevices in the system.

While the generator is deployed described above, the detectors areunfolded 1045. The detectors may be positioned in a variety of ways, asearlier described, including a linear or, using a suitable hydraulicmechanism, in an approximate “C” shape. Shown in FIG. 11 is a processflow diagram of the detector deployment process. Stabilizing feet arefirst deployed 1105 to provide stability to the trailer as it deploysthe detector structure. One of ordinary skill in the art wouldappreciate that the objective of deploying stabilizing feet is to widenthe trailer support base and distribute weight to increase stability andlessen the likelihood of tipping. Other mechanisms could be used tostabilize the trailer structure, including, for example, a hydraulicjack that lifts the trailer up so that the trailer now rests on asupport platform instead of on the wheels; hydraulic brakes that areengaged once the trailer has been suitably positioned such that thebrakes cusp the trailer wheels preventing any movement of the wheels; orsimply a pair of wheel-stops that can be manually placed in front and atthe rear of front and rear wheels respectively preventing anytranslational motion of the wheels.

Once the trailer is stable, the reversible electric motor of thedetector hydraulic system is turned on 1110. The motor starts 1115 thehydraulic pump that fills 1120 the hydraulic actuator with pressurizedhydraulic fluid. This moves 1125 the hydraulic piston, attached to thedetector through a slider ball, causing the detector to unfold 1130upwards. After unfolding the detector panel to a suitable position, thedetector panel is latched 1135 in order to hold it in the requiredunfolded position. A similar process is carried out to unfold the bottompanel of the detector system.

Once the radiation source box is placed opposite to the detector arrayand the array box is fully deployed, alignment 1040 steps are carriedout comprising of: adjusting the vertical height of the radiation sourcebox using leveling mechanisms such as leveling screws or any otherleveling means known to a person of ordinary skill in the art; andalignment of the radiation beam with respect to the detectors.

FIG. 12 is an exemplary embodiment of the radiation source box 11,showing leveling screws 5, 6, 7 and 8 that can be turned to manipulatethe vertical height of the source box 11 and an array of laser pointers9 built into the collimator 10 to facilitate proper alignment of theradiation beam 12 with the detectors. In one embodiment, opticaltriangulation method is used for aligning the plane of the radiationbeam with a predefined “zero” or “idealized centerline” of the detectorsystem. Such optical triangulation techniques, as known to a person ofordinary skill in the art, use a source of light such as a laser pointerto define the radiation beam path. These laser pointers are directed toimpinge on a predefined “zero” of the detectors. The “zero” of thedetectors maybe a spot representing the centroid of the detector systemor an idealized centerline representing a spatial x-y locus of an idealfan beam plane intersecting the plane of the detectors substantiallyorthogonally. In one arrangement, the spatial position of the laserpointers impinging on the detectors is sensed by an array ofphoto-electric diodes of the detector system that send the correspondingposition signals to a computer housed within the trailer. The computercompares the spatial position of the laser pointers with a predefined“zero” of the detector system and sends correction control signals tothe source box through the control cable (attached to the boom) foradjustments till the laser pointers are reasonably lined-up with thedetector system

Depending on conditions, other system elements may be deployed to enablethe screening process. Such elements may include surveillance systemssuch as the closed-circuit television (CCTV) to monitor area around thescanner to control the exclusion zone, a lighting system and a wirelessnetwork. The lighting system may be required to facilitate nightoperation. In a preferred embodiment the analysis of the scanned imagesof an OUI are done by an analyst seated inside the inspection trailer.However, in another embodiment a separate command center mayalternatively or additionally be located away from the scanner,preferably outside the exclusion zone, where a similar analysis ofscanned images may be done. In such an arrangement wireless networks mayadditionally be needed to transfer data from the scanner system to thecommand center.

After deploying the system as described above, an operator may undertakethe following procedure to examine an OUI using the present invention.As used in this description, an OUI is any receptacle for the storage ortransportation of goods, and includes freight pallets as well asvehicles, whether motorized or drawn, such as automobiles, cabs andtruck-trailers, railroad cars or ship-borne containers and furtherincludes the structures and components of the receptacle.

Referring back to FIG. 5, a side elevation view of the system of oneembodiment of the invention during operation is shown. The OUI in thisillustration is a vehicle 20 that is being towed between the source 11and detectors 16 by the tug-vehicle 10. In a preferred arrangement thetug-vehicle 10 is the same vehicle that was earlier used to transportthe inspection trailer 15 to the site. Thus the tug-vehicle 10 servesthe twin purpose of not only transporting the inspection trailer 15 butalso to tow an OUI, such as vehicle 20, during the scanning process toprovide a relative motion between an OUI and the source 11/detector 16system. The mechanism used to attach the tug-vehicle 10 to the trailer15 and then to an OUI during operation may be different. For example,one or more wheel catchers 22 that cups one or more wheels of an OUI,thereby allowing the tug vehicle 10 to pull the OUI by dragging thewheel catcher 22, may be used to tow the inspected vehicle 20.Similarly, other attachment mechanisms may alternatively be used, aswould be known to persons ordinarily skilled in the art.

During the scanning operation, the source 11 and detectors remainstationary and aligned with respect to each other while the OUI, whichis a vehicle 20 in this case, is made to move. In a preferredembodiment, the motion of the vehicle 20 is kept steady and at aconstant velocity such as at or around 2 km/hr. Since, irregularities inthe motion of the vehicle 20 may result in distortions in the scannedimage, the motion is preferably made as regular, even and constant asfeasible using known control systems such as by engaging the tug-vehicle10 in “auto speed” mode. In alternate embodiments, to scan at varyingspeeds depending on the speed of the tug-vehicle 10, irregularities ofmotion are measured and the radiographic image is correspondinglycorrected. To accomplish this, a telemetry mechanism may be used torelay the speed of the tug-vehicle 10 to the inspection trailer 15. Forexample, one or more motion encoders can be affixed to one wheel of thetug-vehicle 10. An encoder measures the rotational velocity of the wheeland transmits a corresponding electrical signal to the imaging system'scomputer housed within the inspection trailer 15. If there is a changein speed, the computer automatically includes a correspondingcompensation in the timing of the detector signals for that location,thereby eliminating image distortions induced due to non-uniform motionof the tug-vehicle 10.

Start-sensors, not shown, are strategically placed to allow an imagingand control system, located within the inspection trailer 15, todetermine that the tug-vehicle 10 has passed the area of beam and thevehicle 20 to be inspected is about to enter the X-ray beam position 30.Thus, as soon as the vehicle 20 to be inspected trips the start-sensors,the radiation source is activated to emit a substantially planarfan-shaped or conical beam 30 (for the duration of the pass) that issuitably collimated for sharpness and made to irradiate substantiallyperpendicular to the path of the vehicle 20.

Since the source 11 and detector 16 remain stationary during thescanning process, collimation can be adjusted to an advantageous minimumsuch that the fan beam emerging out of the collimator just covers thedetectors 16. Apart from using a collimator at the source of radiation,in an alternate embodiment, another collimator arrangement can beadditionally provided integral to the detector system 16 so that thewidth of the fan beam finally striking the detectors 16 may be furtherchanged. As known in the art, X-ray scanning operates on the principlethat, as X-rays pass through objects, some get stopped, some passthrough, and some get deflected owing to a number of different physicsphenomena that are indicative of the nature of the material beingscanned. In particular, scattering occurs when the original X-ray hitsan object and is then deflected from its original path through an angle.These scatter radiations are non-directional and proportional to thetotal energy delivered in beam path. A narrowly collimated beam willkeep the overall radiation dose minimal and therefore also reduce theamount of scatter radiation in the area surrounding the scanner. This,in one arrangement, is achieved by using an adjustable collimator with along snout.

Also, the fan angle of the fan beam 30 is wide enough so that theradiation from the source 11 completely covers the cross section of thevehicle 20 from the side and the radiation is incident on theapproximately “C”-shaped radiation detectors 16. It would also bepossible to make the fan angles of the source 11 smaller than would benecessary to encompass the entire cross-section of the articles beinginspected, in which case the source 11 could be mounted so as to bepivotable around an axis that is essentially parallel to the directionof motion of the vehicle 20. Thus, by pivoting the source 11, theentirety of the cross section of the vehicle 20 can be penetrated by theradiation.

At any point in time when the source 11 is on, the detectors 16 aresnapshots of the radiation beam attenuation in the vehicle 20 for aparticular “slice” of the vehicle 20 under inspection. Each slice is abeam density measurement, where the density depends upon beamattenuation through the vehicle 20. The radiation detectors 16 convertthe lateral radiation profile of the vehicle 20 into electrical signalsthat are processed in an image processing system, housed in theinspection trailer 15, while the vehicle 20 is being conducted past thesource 11 and the radiation detector 16.

In a second embodiment, the present invention is directed towards arelocatable cargo inspection system that employs a single boom attachedto a truck that is capable of receiving and deploying the boom. The boomcomprises a plurality of radiation detectors and a source. The boom ispreferably installed in the rear of the truck to minimize radiationdosage to the driver and is capable of being folded into the truck andfolded out, thus forming an inverted “L” on either the driver orpassenger side.

The single boom structure permits the source, positioned at the base ofthe connecting structure, to rigidly align with the detector array, alsopermitting the unit to operate with a narrower beam width and a lowerradiation level. In addition, the position of the source at the base ofthe connecting structure enables a larger field of view relative toconvention systems having the source on the vehicles. The sourcepreferably extends to a height as low as six inches off the ground.Reference will now be made in detail to specific embodiments of theinvention. While the invention will be described in conjunction withspecific embodiments, it is not intended to limit the invention to oneembodiment.

Referring to FIG. 13, the schematic representation of an exemplaryembodiment of the integrated single boom cargo scanning system of thepresent invention is depicted. The self-contained inspection system 1300of the present invention comprises, in a preferred embodiment, aninspection module in the form of a rig/tractor trailer 1301, capable ofbeing driven to its intended operating site. The vehicular portion ofthe system and the inspection module portion of the system areintegrated into a single mobile structure. The integrated modular mobilestructure serves as a support and carrier structure for at least onesource of electromagnetic radiation; and a possible radiation shieldplate on the back of the driver cabin of the vehicle, used to protectthe driver from first order scatter radiation.

The inspection or scanning module 1300 is custom-built as an integratedmobile trailer 1301 and can provide support for a single boom 1302 todeploy a power cable (not shown) to at least one source of radiation1304 during operation. In addition, boom 1302 houses an array ofdetectors 1303. In a preferred embodiment, boom 1302 is attached totrailer 1301, capable of receiving and deploying the boom. Boom 1302 ispreferably installed and located in the back of trailer 1301 to minimizeradiation dosage to driver in trailer cab 1305. Trailer 1301 also housesan operator/analyst cabin including computer and imaging equipment alongwith associated power supplies, air conditioning and power generatingequipment (not shown) in accordance with the understanding of a personof ordinary skill in the art of X-ray generation. Depending onconditions, other system elements may be deployed to enable thescreening process. Such elements may include surveillance systems suchas the closed-circuit television (CCTV) to monitor area around thescanner to control the exclusion zone, a lighting system and a wirelessnetwork. The lighting system may be required to facilitate nightoperation. In a preferred embodiment the analysis of the scanned imagesof an OUI are done by an analyst seated inside the inspection trailer.However, in another embodiment a separate command center mayalternatively or additionally be located away from the scanner,preferably outside the exclusion zone, where a similar analysis ofscanned images may be done. In such an arrangement wireless networks mayadditionally be needed to transfer data from the scanner system to thecommand center. In addition, boom 1302 is capable of being folded intotrailer 1301 in a “stowed” position or folded out from trailer 1301 in a“deployed” position, on either the driver or passenger side.

The radiation source box 1304 is located on the same single boom 1302 asthe detection system 1303. Thus, while source box 1304 is locatedopposite the detector system 1303 at a distance that is suitable toallow Object under Inspection (“OUI”) to pass in the area 1306 betweenthe source 1304 and detector array 1303 during the scanning process, itis located on the same boom 1302 to eliminate the need for alignment.The radiation source, in a preferred embodiment is an X-ray generator.In yet another preferred embodiment, the radiation source is a linearaccelerator (LINAC). If the X-ray generator or LINAC is mounted on thesame single boom as the detector arrays, the need for sophisticatedalignment systems each time the system is deployed is eliminated. Thus,the radiation source and detectors are substantially permanently alignedon the same single boom. The feature also allows for scanning at variousdegrees of offset, again without the need to realign the LINAC or X-raygenerator and detectors.

An OUI could be any type of object, including cars, trucks, vans, cargocontainers, mobile pallets with cargo, or any other type of cargoobject. During the scanning process, the OUI remains in the areademarcated by the deployed boom 1306 as a fixed piece of cargo while theself-contained inspection rig/tractor trailer 1300 moves over the OUI.Alternatively, the self-contained inspection rig/tractor trailer 1300can remain in place while a piece of cargo is driven, moved, dragged,tagged, and/or lifted through the scanning region 1306. As theself-contained inspection trailer 1300 is moved over OUI, an image ofthe OUI is produced on the inspection computers housed within thetrailer showing the radiation-induced images of the articles and objectscontained within the OUI (not shown). Therefore, in a preferredembodiment, the system is designed such that the self-containedinspection trailer moves over the stationary object (OUI).

The source of radiation includes radio-isotopic source, an X-ray tube,LINAC or any other source known in the art capable of producing beamflux and energy sufficiently high to direct a beam to traverse the spacethrough an OUI to detectors at the other side. The choice of source typeand its intensity and energy depends upon the sensitivity of thedetectors, the radiographic density of the cargo in the space betweenthe source and detectors, radiation safety considerations, andoperational requirements, such as the inspection speed. The system ofthe present invention could employ source-based systems, for example,cobalt-60 or cesium and further employ the required photomultipliertubes (PMT) as detectors. If a linear accelerator (LINAC) is optionallyemployed, then photodiodes and crystals are used in the detector. One ofordinary skill in the art would appreciate how to select a radiationsource type, depending upon his or her inspection requirements.

In one embodiment, where OUI is a large sized container or car thathighly attenuates the X-ray beam, the radiation could be from an X-raytube operating at a voltage in substantial excess of 200 keV, and mayoperate in varying regions, including 450 keV, 3 MeV, 4.5 MeV, and even,but not limited to 6 MeV.

FIGS. 14 and 15 depict a side view illustration and top viewillustration, respectively, of one embodiment of the vehicle of thepresent invention in a folded, or “stowed” position. In this position,the single boom 1401, 1501 detector arrays 1402, 1502 and radiationsource 1403 fold onto the flatbed 1404, 1504 of the vehicle/trailer1405, 1505. Thus, the detector arrays 1402, 1502 and radiation source1403 are preferably positioned in a manner, such that when folded orstored, permit trailer 1405, 1505 to travel safely on public roadways.Additionally, the detectors are preferably integrally formed to enablefor stable, yet rapid deployment. The detectors may also optionally belinear arrays that extend substantially parallel to the base of thetrailer and, when deployed, extend substantially orthogonal to the baseof the trailer.

Referring to FIG. 16, a side perspective view of the single boom cargoscanning system of the present invention in a deployed or “unfolded”position is depicted. In a preferred embodiment, trailer 1601 compriseschassis 1602, having a front face 1603, a rear end 1604, and sides 1605.Trailer 1601 also comprises a trailer (driver's) cab 1610 and a singleboom 1611. In a preferred position, boom 1611 extends centrally abovechassis 1602 from a point (shown as 1612) approximately above rear axle1607, thus allowing it to rotate in the desired directions. Boom 1611has a proximal end attached to the vehicle and a distal end physicallyattached to the radiation source. Boom 1611 preferably consists of ahollow cylindrical main body 1613, a connecting structure 1614, an outerarm 1615, and a telescopic arm 1616. Outer arm 1615 protrudes from theconnecting structure 1614 to preferably form an L-shaped structure. Bothouter arm 1615 and connecting structure 1614 comprise detector panels.

Outer arm 1615 is further connected to telescopic arm 1616. Hydrauliccylinders or actuators (not shown) are provided for the turning movementof boom 1611, outer arm 1615 and telescopic arm 1616. In order tofacilitate push-button deployment and the dispensing away of assemblingtools or skill, the action of folding or unfolding of the outer arm 1615containing the detector array is enabled by a suitable hydraulic systemknown to a person of ordinary skill in the art. One exemplary hydraulicsystem for unfolding the detector panels comprises a reversibleelectrical motor to drive a hydraulic pump that in turn provideshydraulic fluid under pressure to a double acting hydraulic actuatorattached to the trailer. When the hydraulic actuator is required tounfold the detector panel, pressurized hydraulic fluid is pumped intothe chamber, engaging a piston to move a slider ball that in turnunfolds the detector panel. Once the detector panel is unfolded throughan acceptable angle, the detector panel is securely latched in positionusing a mechanical latch such as a simple hook and peg system or anyother latching arrangement known to one of ordinary skill in the art. Asimilar arrangement can be used to deploy the remaining detector panels.

FIG. 17 depicts the top view of the single boom cargo scanning system ofthe present invention, in a partially deployed position. Outer arm 1701is visible and opens, thus making angle 1702 with respect to trailer1703. In a preferred embodiment, the radiation source box (not shown) islocated on the same single boom at the detector boxes (as describedabove), thereby eliminating the need for sophisticated alignment systemseach time the system is deployed. The radiation source is located on oneside of the boom while the detectors are located on the other. Therotating boom allows for the source of radiation to be positionedopposite to the area of the boom supporting the detectors. The radiationsource is permanently fixed in alignment relative to the detector boom.The radiation source is rotated from the storage position to thedeployed position. The electrical power generator is turned on toprovide power to the electrical devices in the system. While thegenerator is deployed, the detectors are unfolded as described above.With the source located on a rotating platform behind the boom post, ashorter boom can optionally be used to enable the requisite distancebetween the source and the detectors. This design also allows forgreater stability, because the position of the radiation source is usedto counterbalance the detector boom.

Referring back to FIG. 16, extension and withdrawal of telescopic arm1616 in relation to the main body 1613 is preferably effectuatedhydraulically using suitable hydraulic cylinders (not shown) in mainbody 1613. Thus, telescopic arm 1616 moves with multiple degrees offreedom. FIG. 18 depicts one exemplary movement of the telescopic arm1801 of the single boom cargo scanning system of the present invention.Telescopic arm 1801 forms an acute angle 1802 with respect to outer arm1803. In FIG. 19, another degree of freedom of the abovementionedtelescopic arm. The telescopic arm 1901 is perpendicular 1902 to theouter arm 1903.

As described in detail above, the detectors preferably comprise panelsthat are capable of being folded, such that, when in a storage position,the detectors recess into the side of the inspection trailer. By formingdetectors such that they can fold in a storage position, it is possibleto produce a compact trailer that can safely, and legally, travelroadways. When unfolded during operation, the detectors assume either alinear or an arched shape.

Now referring to FIG. 20, a rear view illustration of the single boomcargo scanning system of the present invention is depicted. As mentionedabove, connecting structure 2001 and outer arm 2002 consist of detectorarray panels 2003. In a preferred embodiment, the detectors assume anapproximate inverted “L” shape, as they are placed on connectingstructure 2001 and outer arm 2002. The preferred inverted “L” shapedetector enables the radiation source to be closer to the targetvehicle, thus allowing higher penetration capability, and provides forcomplete scanning of the target vehicle without corner cutoff.

At its distal end, the telescopic arm 2005 is attached to radiationsource 2006 and is deployed from boom 2007, once rotated into desiredscanning positions. Single boom 2007 allows for source 2006, positionedat the base of the telescopic arm 2005, to rigidly align with detectorarray 2003.

An array of laser pointers emitting laser radiation is built into thecollimator to facilitate proper alignment of the radiation beam with thedetectors. In one embodiment, optical triangulation method is used foraligning the plane of the radiation beam with a predefined “zero” or“idealized centerline” of the detector system. Such opticaltriangulation techniques, as known to a person of ordinary skill in theart, use a source of light such as a laser pointer to define theradiation beam path. These laser pointers are directed to impinge on apredefined “zero” of the detectors. The “zero” of the detectors may be aspot representing the centroid of the detector system or an idealizedcenterline representing a spatial x-y locus of an ideal fan beam planeintersecting the plane of the detectors substantially orthogonally. Inone arrangement, the spatial position of the laser pointers impinging onthe detectors is sensed by an array of photo-electric diodes of thedetector system that send the corresponding position signals to acomputer housed within the trailer. The computer compares the spatialposition of the laser pointers with a predefined “zero” of the detectorsystem and sends correction control signals to the source box throughthe control cable (attached to the boom) for adjustments until the laserpointers are reasonably lined-up with the detector system.

Radiation source box 2006, attached to telescopic arm 2005, emitspenetrating radiation beam 2008 having a cross-section of a particularshape. Several embodiments for the radiation source, but not limited tosuch embodiments, are described in further detail below. The more rigidalignment of radiation source 2006 with detector array 2003 permits thescanning system of the present invention to operate with a narrower beamwidth and a lower radiation level. Positioning source 2006 at the baseof telescopic arm 2005 also permits a larger field of view relative tothe conventional systems having the source on the vehicle. Also, source2006 can extend as low as six inches off of floor level, shown as 2009,and can provide the under-carriage view 2010 of OUI 2011.

Optionally, boom 2007 deploys and permits detector array 2003 andradiation source box 2006 to extend outward, preferably resting at anangle of about 10 degrees relative to the plane perpendicular to OUI2011. This permits for easy viewing of dense material and hiddencompartments (not shown). The heaviest material in cargo is usuallylocated at the bottom floor of the truck. For example, in one particularembodiment, a linear accelerator (LINAC) is employed. The zero degreecenter point of the beam is the strongest portion of the beam. In orderto capture scans of the floor level of the truck, the radiation sourcebeam is positioned to orientate 15 degrees downward to detect materialsin the undercarriage and then 30 degrees upward to detect the higherportions of the load. This ensures that the strongest X-rays (at thezero degree position or, center of the X-ray tube) are oriented at thefloor level of the truck, which is critical to the performance of thesystem as the densest and most difficult portion of a truck to image isthe floor level.

During the scanning operation, radiation source 2006 and detector array2003 are activated and the scanning trailer is driven over the OUI, suchthat the objects get positioned between the trailer and radiation source2006. In a preferred embodiment, during the scanning operation, thesource and detectors remain stationary and aligned with respect to eachother while mobilized and passed over the OUI. In a preferredembodiment, the motion of the scanner is kept steady and at a constantvelocity. Since, irregularities in the motion of the vehicle may resultin distortions in the scanned image, the motion is preferably made asregular, even and constant as feasible using known control systems suchas by engaging the trailer motor in “auto speed” mode. As described ingreater detail below, the scanning system is manipulated via a closedloop method to automatically correct images for the different speeds ofoperation of the scanning trailer. Such speed control system is acombination of mechanical, electrical, and software design.

Since the source and detector remain in a relative stationary and fixedposition during the scanning process, collimation can be adjusted to anadvantageous minimum such that the fan beam emerging out of thecollimator just covers the detectors. The collimation mechanism employedis preferably a rotating wheel or any other suitable mechanism as knownto the person of ordinary skilled in the art. Referring to FIG. 21, arotating collimation wheel of one embodiment of the present invention isdepicted. Rotating wheel 2101 is used to develop pencil beam 2102, whichpasses through the object. A series of tubular collimators 2103 aredistributed as spokes on rotating wheel 2101. Cross-section of pencilbeam 2102 is substantially rectangular, but is not limited to suchconfigurations. The dimensions of pencil beam 2102 typically define thescatter image resolution, which may be obtained with the system.

As known in the art, X-ray scanning operates on the principle that, asX-rays pass through objects, the radiation gets attenuated, absorbed,and/or deflected owing to a number of different physical phenomena thatare indicative of the nature of the material being scanned. Inparticular, scattering occurs when the original X-ray hits an object andis then deflected from its original path through an angle. These scatterradiations are non-directional and proportional to the total energydelivered in beam path. A narrowly collimated beam will keep the overallradiation dose minimal and therefore also reduce the amount of scatterradiation in the area surrounding the scanner, thereby reducing the“exclusion zone”.

During deployment the inspection trailer is driven to the inspectionsite and the radiation source and detector booms are positioned. Becausethe trailer moves over the OUI, it does not need to be positionedstrategically to allow for high throughput. Rather, the trailer may bedriven over any OUI, located anywhere, given that there is space for theinspection trailer to pass without disrupting port activities. Anotheraspect that may influence the decision of positioning the trailer couldbe the availability of a large enough area, called the “exclusion zone”,around the scanner system. The exclusion zone is an area around thescanner in which general public are not authorized to enter due to thepossibility of their getting exposed to doses of radiations scatteredduring the scanning process. The exclusion area is dependent upon themagnitude of current setting the intensity of the radiation source.

FIG. 22 illustrates a preferred embodiment of the detector array 2201 asemployed in the single boom cargo scanning system of the presentinvention. The detectors 2202 may be formed by a stack of crystals thatgenerate analog signals when X-rays impinge upon them, with the signalstrength proportional to the amount of beam attenuation in the OUI. Inone embodiment, the X-ray beam detector arrangement consists of a lineararray of solid-state detectors of the crystal-diode type. A typicalarrangement uses cadmium tungstate scintillating crystals to absorb theX-rays transmitted through the OUI and to convert the absorbed X-raysinto photons of visible light. Crystals such as bismuth germinate,sodium iodide or other suitable crystals may be alternatively used asknown to a person of ordinary skill in the art. The crystals can bedirectly coupled to a suitable detector, such as a photodiode orphoto-multiplier. The detector photodiodes could be linearly arranged,which through unity-gain devices, provide advantages overphoto-multipliers in terms of operating range, linearity anddetector-to-detector matching. In another embodiment, an area detectoris used as an alternative to linear array detectors. Such an areadetector could be a scintillating strip, such as cesium iodide or othermaterials known in the art, viewed by a suitable camera or opticallycoupled to a charge-coupled device (CCD).

FIG. 23 is a detailed illustration of one preferred embodiment of thedetectors 2300 employed in the detector array 2305, as shown in FIG. 21.The detectors are preferably angled at 90 degrees relative to theradiation source focal point. The radiation scattered from the radiationsource beam is detected by the strategically positioned detectors, thusimproving image quality.

FIG. 24 is a detailed illustration of another preferred embodiment ofthe detectors employed in the detector array shown in FIG. 22, where thedetectors are arranged in a dual row. Detector array 2401 preferablycomprises a dual row of detectors 2402 that are blended together in aninterlacing fashion to allow better resolution using a suitablealgorithm. The focus algorithm provides automatic means to combine theimages resulting from the dual row of detectors 2402, which are athalf-detector offset from each other, into a single row allowing fordouble resolution compared to a single row of detectors. This blendingmethod eliminates jagged edges in the resultant images from the use ofthe two detector rows 2402.

At any point in time when the radiation source is on, the detectors aresnapshots of the radiation beam attenuation in the OUI for a particular“slice” of the OUI. Each slice is a beam density measurement, where thedensity depends upon beam attenuation through the OUI. The radiationdetectors convert the lateral radiation profile of the OUI intoelectrical signals that are processed in an image processing system,housed in the inspection trailer, while the OUI is being conducted pastthe source and the radiation detector.

The X-ray image processing and control system, in an exemplaryembodiment, comprises a computer and storage systems which records thedetector snapshots and software to merge them together to form an X-rayimage of the vehicle which may further be plotted on a screen or onother media. The X-ray image is viewed or automatically analyzed by OUIacquisition system such as a CRT or monitor that displays the X-rayimage of the vehicle to an operator/analyst. Alternatively, the OUIacquisition systems may be a database of X-ray images of desiredtargets, such as automobiles, bricks or other shapes that can becompared with features in the image. As a result of this imaging, onlyarticles that were not contained in the reference image of the containeror vehicle are selectively displayed to an operator/analyst. This makesit easier to locate articles that do not correspond to a referencecondition of the container or vehicle, and then to conduct a physicalinspection of those articles. Also, for high-resolution applications,the electronics used to read out the detector signals may typicallyfeature auto-zeroed, double-correlated sampling to achieve ultra-stablezero drift and low-offset-noise data acquisition. Automatic gain rangingmay be used to accommodate the wide attenuation ranges that can beencountered with large containers and vehicles.

FIG. 25 is a block diagram of an exemplary X-ray image processing anddisplay unit of the single boom cargo scanning system of the presentinvention. X-ray image display and processing unit 2500 includesdetectors 2501 coupled through data processing units (DPU) 2502, drivers2503, interface card 2504 and computing device 2505. Computing device2505 processes discrete photo current integration information receivedfrom the detectors 2501 via interface card 2504, which is attached tocomputing device 2505. Display device 2506, attached to computing device2505, renders the image of the contents of the target object uponreceiving information from computing device 2505. The detector arrayincludes a plurality of detectors. The detectors 2501 are coupled ingroups of data processing circuits (not shown). It is preferred thatthree groups of detectors 2501 are employed, wherein the number ofdetectors 2501 in use is dependent upon the height of the OUI (notshown), and the resolution (i.e. number of pixels) of the image desired.In a preferred configuration, three data processing units 2502 arecoupled to line driver 2503, which is coupled to network interface 2504.Interface 2504, such as but not limited to RS-485, is embodied on acircuit card located within computing device 2505.

Computing device 2505 is preferably a microprocessor based personalcomputer system and operates under the control of a software system.Computing device 2505 thus receives detector pulses 2507 from each ofthe data processing units 2502, in response to the detection ofindividual photons 2508 by the detectors. The software system processesthe incoming detector pulses 2507, evaluates their relative amplitudes(i.e. energies), and generates a radiographic image-like display outputsignal, which is coupled to the graphical display device 2506, thusgenerating a graphical representation of the densities within the OUI.

The present invention generates a graphical representation, i.e., animage, of the densities of the contents of the vehicle under inspection.This allows for easy visual interpretation of the results of thescanning of the OUI.

Advantageously, the preferred software system also causes the display ofa reference image simultaneously with the image generated in response tothe vehicle under inspection, so that an operator of the presentembodiment can easily make a visual comparison between what an object ofthe type being inspected should “look like”, and what the OUI actually“looks like”. Such “side-by-side” inspection further simplifies thedetection of contraband using the present embodiment.

The vertical linear array configuration of the detector array isdesigned to provide a resolution of grid points spaced approximatelyevery 5 cm along the length and about 4.3 cm along the height of thetarget OUI. This resolution is adequate to achieve a detectability limitof less than half a kilogram of contraband per 4.3 cm by 5 cm gridpoint(or pixel). The pixel size can be easily varied by appropriatelyselecting the location of the radiation source and the detectors withinthe detector array, and by varying the distance between inspectionspoints longitudinally (via choice of counting interval and scan speedalong the length of the target vehicle). A suitable algorithm implementsa correction that takes into account the speed of the scanning trailerunder motion, the scanning rate (i.e., number of lines scanned persecond), detector size, and distance between the detectors.

In a preferred embodiment, a closed loop method is employed toautomatically correct images for the varying speeds of operation of thescanning system. The speed control system is a function of mechanical,electrical, and software components of the scanning system of thepresent invention.

Referring to FIG. 26, a flow chart depicts the operational steps of thesingle boom cargo scanning system of the present invention once theimage generation program is executed. In step 2601, the single boomscanning system of the present invention initiates image generation. Instep 2602, movement of the trailer containing the single boom begins. Inanother embodiment, where the OUI is optionally driven underneath andthrough the self-contained inspection system, start-sensors may bestrategically placed to allow an imaging and control system, locatedwithin the inspection trailer, to determine that the OUI cab, in thecase of a vehicle, has passed the area of beam and the vehicle to beinspected is about to enter the X-ray beam position. Thus, as soon asthe vehicle to be inspected trips the start-sensors, the radiationsource is activated to emit a substantially planar fan-shaped or conicalbeam for the duration of the pass) that is suitably collimated forsharpness and made to irradiate substantially perpendicular to the pathof the vehicle.

In step 2603, the detectors are calibrated by irradiation with theradiation source at a point along the track prior to the radiationsource arm and detector array arm reaching the OUI. In other words,calibration occurs before the OUI is interposed between the detectorarray and the radiation source. The irradiation of the detector arraysets a baseline, in step 2604 of radiation (or “white” photo currentintegration level) analogous to a density in the OUI approximately zeroand a maximum photo current integration level. In step 2605, three photocurrent integration measurements are preferably made in this manner foreach detector. In step 2606, measurements are arranged for each detectorand stored in an array having a white level element for each detector.

In step 2607, the horizontal position is set to zero. The horizontalposition corresponds to a position along the scanning track, randomlyselected, at which density measurements are taken for the first time.This horizontal position should be at a point before the OUI isinterposed between the detector array and the radiation source. In step2608, the detector measurement is set to zero, corresponding to thefirst detector in the detector array to be queried for a photo currentintegration level. The detector is queried in step 2609 for a photocurrent integration level and is instructed to restart measurement. Instep 2610, the detector restarts measurement in response to theinstruction to restart. In step 2611, photo current integration leveldetermined in step 2609 is passed to the measurement device. In step2612, the level of photo current integration measured is stored in anarray and is then converted into a pixel value in step 2613. Theconversion is achieved by mapping the amount of photo currentintegration to a color, for display on the display device. In step 2614,the detector number queried is converted into a vertical position on thescreen display. The horizontal position of the radiation source and thedetector array along the scanning track is converted to a horizontalposition on the screen display in step 2615. Once the vertical andhorizontal positions are ascertained, a pixel is illuminated in step2616 using the color corresponding to the photo current integrationlevel.

In step 2617, a determination is made as to whether all of the detectorsin the detector array have been queried for a photo current integrationlevel for the current horizontal position. If all the detectors have notbeen queried, the detector number to be queried is incremented in step2618. The image generation program continues by querying the nextdetector in the detector array for the photo current integration leveland by instructing such detector to restart measurement as in step 2610.The image generation program continues executing from this step, asdescribed in detail above.

If all the detectors within the detector array have been queried for thecurrent horizontal position, the horizontal position is incremented instep 2619. In step 2620, a determination is made as to whether or notthe radiation source arm and the detector array arm of the single boomscanning trailer are still in motion. If the boom components are stillin motion, the detector to be queried is reset to zero and the imagegeneration program continues, as shown in step 2621. If the single boomscanning system has stopped moving, the image generation program isterminated in step 2622.

In a third embodiment, the present invention is directed towards a cargoinspection system and method for generating an image representation oftarget objects using a radiation source having a boom connected to thehousing and at least one source of radiation. The boom comprises aplurality of radiation detectors with the connecting structure at itsproximal end and a distal end (vertical boom tube element) that islaterally opposite the vehicle when deployed. In a preferred embodiment,the inspection system is in the form of a mobile rig/tractor trailercapable of being driven to its intended operating site. In addition, thecomponents of the system are preferably housed on a single mobilevehicular unit. The inspection module is custom-built and attached to amobile trailer or truck and can provide support for a plurality ofdetector arrays and a boom to deploy a power cable to at least onesource of radiation during operation. The radiation source is located ona rotatable platform integrally connected to the proximal end(connecting structure) of the boom which is attached to the vehicle. Thestructure can be rotated from a stored position to a deployed positionon either side of the support vehicle to allow scanning to be conductedon either side of the vehicle.

The configuration of the preferred third embodiment is designed suchthat it reduces the overall weight and dimensions of the scanningsystem; rigidly attaches the radiation source to the collimator tofacilitate permanent alignment of the radiation beam with the detectors,thus eliminating the need for continual alignment and allowing for amore precise radiation source beam via collimation techniques; andenables lower scanning heights and better visibility of the floor levelof the object or vehicle under inspection via a lower mounted design ofthe radiation source box.

The single boom tube is a hollow body, preferably cylindrical, andcomprises the proximal end or connecting structure of the boom. In apreferred embodiment, it is used to support a collimator, providing fora more precise X-ray beam critical to reducing scattered X-ray and theX-ray dose to the VUI or OUI. The presence of the post collimationweight is also favorable, as it counterbalances the boom weight. Thestructure also permits the radiation source, positioned at the base ofthe connecting structure, to rigidly align with the detector array, thuspermitting the unit to operate with a narrower beam width and a lowerradiation level. In addition, the position of the source at the base ofthe connecting structure enables a larger field of view relative toconventional systems having the source on the vehicles. Reference willnow be made in detail to specific embodiments of the invention. Whilethe invention will be described in conjunction with specificembodiments, it is not intended to limit the invention to oneembodiment.

Referring to FIG. 27, a rear perspective view of the third embodiment ofan exemplary self-contained inspection system of the present inventionis depicted. The self-contained inspection system 2700 of the presentinvention comprises, in a preferred embodiment, an inspection module inthe form of a rig/tractor trailer 2701, capable of being driven to itsintended operating site. The vehicular portion of the system and theinspection module portion of the system are integrated into a singlemobile structure. The integrated modular mobile structure serves as asupport and carrier structure for at least one source of electromagneticradiation and a possible radiation shield plate on the back of thedriver and/or operator cabin of the vehicle, used to protect the driverand/or operator from first order scatter radiation.

The self-contained inspection system 2700 is custom-built as anintegrated mobile trailer or truck 2701 and can provide support for atower boom 2702 to route power and signal cables (not shown) toradiation detector array 2703 during operation. In a preferredembodiment, boom 2702 is attached to trailer 2701, which is capable ofreceiving and deploying the boom. Boom 2702 is preferably installed andlocated in the back of trailer 2701 to minimize radiation dosage to thedriver in trailer cab (not shown). In addition, boom 2702 is capable ofbeing folded into trailer 2701 in a “stowed” position or folded out fromtrailer 2701 in a “deployed” position, on either the driver or passengerside. Thus, since boom 2702 can be deployed on either side of thesupport vehicle, scanning can be conducted on either side of thevehicle, yielding greater flexibility in operation. Thus, the rotatingboom elements are dual-sided and may be deployed or “unfolded” on eitherside of the vehicle.

In addition, boom 2702 houses radiation detector array 2703. Radiationsource box 2704 is located on a rotatable platform connected to and partof the same detector array boom, and can be rotated from a storedposition to a deployed position.

As described with reference to FIG. 16 above, the boom comprises aproximal end attached to the vehicle and a distal end. In this preferredembodiment, the proximal end or connecting structure that is attached tothe vehicle also comprises a rotatable platform base, which houses theradiation source box. Thus, the boom comprises a hollow and preferablycylindrical or square main body (connecting structure), an outer armwhich is preferably horizontal, and a telescopic arm (hereinafter, alsoreferred to as the vertical boom tube element) which is physicallyattached to the outer arm. The outer arm protrudes from the connectingstructure and further connects to the telescopic arm (vertical boom tubeelement), to preferably form the “C”-shape structure. The telescopic armis located at the distal end of the detector array boom. The detectorpanels are located on both the outer arm and the telescopic arm of theboom, laterally opposite to the connecting structure where the radiationsource box is housed on a rotatable platform.

Radiation source box 2704 is preferably positioned on rotating platformbase 2708, which is integrally connected to the connecting structure ofboom 2702. Radiation source box 2704 is located laterally oppositedetector array system 2703 (also on tower boom 2702) at a distance thatis suitable to allow Object under Inspection 2707 (“OUI”) to pass in thescanning area 2706 between the radiation source 2704 and detector array2703 during the scanning process. The rotating platform base 2708 allowsfor the source of radiation to be positioned laterally opposite to theside of the trailer supporting the detectors, and can be rotated inposition to allow for scanning on either side of the vehicle (operatoror passenger) to allow for greater flexibility. The radiation source ispermanently fixed in alignment relative to the detector boom. When inuse, the radiation source is rotated, on the platform boom, from thestorage position to the deployed position. The electrical powergenerator is turned on to provide power to the electrical devices in thesystem. While the generator is deployed, the detectors are unfolded aswill be described in further detail below. The relative positions of theradiation source box and detectors on the same boom enables use of ashorter boom. With the radiation source located on a rotating platformbehind the boom post, a shorter boom may optionally be employed tocreate the requisite scanning space 2706 between source and detectors.This design also allows for greater stability because the radiationsource, as will be described with respect to FIG. 28, is used tocounterbalance the detector boom. In addition, the use of the radiationsource and its associated components to counterbalance the weight of thedetector boom allows the width of the deployed boom to be reduced byapproximately 2.5 meters over alternate designs. The boom, as used here,is a support structure, but not limited to this particular embodiment.

Trailer 2701 also houses an operator/analyst cabin including computerand imaging equipment along with associated power supplies, airconditioning and power generating equipment (not shown) in accordancewith the understanding of a person of ordinary skill in the art of X-raygeneration. Depending on conditions, other system elements may bedeployed to enable the screening process. Such elements may includesurveillance systems such as the closed-circuit television (CCTV) tomonitor area around the scanner to control the exclusion zone, alighting system and a wireless network. The lighting system may berequired to facilitate night operation. In a preferred embodiment theanalysis of the scanned images of an OUI are done by an analyst seatedinside the inspection trailer. However, in another embodiment a separatecommand center may alternatively or additionally be located away fromthe scanner, preferably outside the exclusion zone, where a similaranalysis of scanned images may be done. In such an arrangement wirelessnetworks may additionally be needed to transfer data from the scannersystem to the command center.

The radiation source, in a preferred embodiment is an X-ray generator.In yet another preferred embodiment, the radiation source is a linearaccelerator (LINAC). The X-ray generator or LINAC is mounted on a singlerotating platform located on the same boom as the detector arrays, thuseliminating the need for sophisticated alignment systems each time thesystem is deployed. Thus, the radiation source and detectors aresubstantially permanently aligned on a single boom. The feature alsoallows for scanning at various degrees of offset, again without the needto realign the LINAC or X-ray generator and detectors.

Object Under Inspection (OUI) 2707 could be any type of object,including cars, trucks, vans, cargo containers, mobile pallets withcargo, or any other type of cargo object. During the scanning process,the OUI remains in the area demarcated by the deployed boom as a fixedpiece of cargo while the self-contained inspection system rig/trailer2701 moves over OUI 2707. Alternatively, the self-contained inspectionsystem rig/tractor trailer 2701 can remain in place while a piece ofcargo is driven, moved, dragged, tagged, and/or lifted through scanningregion 2706. As the self-contained inspection rig/trailer 2701 is movedover OUI 2707, an image of the OUI 2707 is produced on the inspectioncomputers housed within the trailer showing the radiation-induced imagesof the articles and objects contained within the OUI (not shown).Therefore, in a preferred embodiment, the system is designed such thatthe self-contained inspection trailer moves over the stationary object(OUI).

The source of radiation includes a radio-isotopic source, an X-ray tube,LINAC or any other source known in the art capable of producing beamflux and energy sufficiently high to direct a beam to traverse the spacethrough an OUI to detectors at the other side. The choice of source typeand its intensity and energy depends upon the sensitivity of thedetectors, the radiographic density of the cargo in the space betweenthe source and detectors, radiation safety considerations, andoperational requirements, such as the inspection speed. The system ofthe present invention could employ source-based systems, for example,cobalt-60 or cesium and further employ the required photomultipliertubes (PMT) as detectors. If a linear accelerator (LINAC) is optionallyemployed, then photodiodes and crystals are used in the detector. One ofordinary skill in the art would appreciate how to select a radiationsource type, depending upon his or her inspection requirements.

In one embodiment, where OUI 2707 is a large sized container or car thathighly attenuates the X-ray beam, the radiation could be from an X-raytube operating at a voltage in substantial excess of 200 keV, and mayoperate in varying regions, including 450 keV, 3 MeV, 4.5 MeV, and even,but not limited to 6 MeV.

Because the radiation source box 2704 is positioned on the proximal endof the boom (connecting structure) that is connected to the truck andlaterally opposite the proximal end (the vertical boom tube element),the radiation source, the optional counterbalance weight, and the postcollimation between the radiation source and the optional counterbalanceweight 2709 all provide significant counterbalance weight to offset thedetector boom weight. Thus, post collimation provides for a more preciseX-ray beam, critical to reducing both scattered X-ray and the X-ray doseto the object under inspection. In most existing systems, the use ofpost collimation at any point beyond the radiation source is prohibitivebecause of the significant impact to the leaning torque of the truck.The post-collimation weight between the radiation source and the hollowcylindrical main body is, preferably, on the opposite side of the truckas the deployed boom (proximal end of boom), thus becoming favorableweight as it acts to counterbalance some of the deployed boom weight. Acounter balance weight 2709 could optionally be used to offset larger orheavier boom structures. Thus, the system of the present invention usesthe positioning of the radiation source to counterbalance the weight ofthe detector boom, thereby adding stability to the system andobfuscating the need for other stabilizing mechanisms.

FIG. 28 is a depiction of a top planar view of a preferred location forthe counterbalance, post-collimation weight 2801 and pre-collimationslot 2803 built into the boom tower 2802 of the preferred thirdembodiment of the present invention. An array of laser pointers emittinglaser radiation may optionally be built into the boom tower collimatorto facilitate proper alignment of the radiation beam with the detectors.In one embodiment, an optical triangulation method is used for aligningthe plane of the radiation beam with a predefined “zero” or “idealizedcenterline” of the detector system. Such optical triangulationtechniques, as known to a person of ordinary skill in the art, use asource of light such as a laser pointer to define the radiation beampath. These laser pointers are directed to impinge on a predefined“zero” of the detectors. The “zero” of the detectors may be a spotrepresenting the centroid of the detector system or an idealizedcenterline representing a spatial x-y locus of an ideal fan beam planeintersecting the plane of the detectors substantially orthogonally. Inone arrangement, the spatial position of the laser pointers impinging onthe detectors is sensed by an array of photo-electric diodes of thedetector system that send the corresponding position signals to acomputer housed within the trailer. The computer compares the spatialposition of the laser pointers with a predefined “zero” of the detectorsystem and sends correction control signals to the source box throughthe control cable (attached to the boom) for adjustments until the laserpointers are reasonably lined-up with the detector system.

The radiation source box (not shown), placed on a rotating platformintegrally connected to the same boom support as the detector array,emits a penetrating radiation beam having a cross-section of aparticular shape. Several embodiments for the radiation source, but notlimited to such embodiments, are described above. The more rigidalignment of the radiation source with the detector array permits thescanning system of the present invention to operate with a narrower beamwidth and a lower radiation level. Positioning the source at the base ofthe boom tower 2802 also permits a larger field of view relative to theconventional systems having the radiation source located on the vehicle.

This permits for easy viewing of dense material and hidden compartments(not shown). The heaviest material in cargo is usually located at thebottom floor of the truck. In a particular embodiment, a linearaccelerator (LINAC) is employed. The zero degree center point of thebeam is the strongest portion of the beam. In order to capture scans ofthe floor level of the truck, the radiation source beam is positioned toorientate approximately 15 degrees downward to detect materials in theundercarriage and then 35 degrees upward to detect the higher portionsof the load. This ensures that the strongest X-rays (at the zero degreeposition or, center of the X-ray tube) are oriented at the floor levelof the truck, which is critical to the performance of the system as thedensest and most difficult portion of a truck to image is the floorlevel.

FIG. 29 illustrates, an exemplary self-contained inspection system 2900of the present invention in a folded or “stowed” position. In thisposition, the boom and detector arrays fold onto the flatbed 2901 of thevehicle/trailer 2902. Traditional self-contained mobile inspectionsystems employ vertical boom tube elements which fold 90 degrees, or atleast substantially parallel to the outer arm or horizontal portion ofthe boom when in a folded or “stowed” position, as shown by way ofreference in FIG. 30. FIG. 30 is a schematic representation of aself-contained inspection system 3000 as in the present invention. Thevertical boom element 3103, however, is folded at the conventional 90degrees and is substantially parallel to the horizontal portion of theboom 3104.

In a preferred embodiment of the present invention, the vertical boomtube element 2903 is folded at an angle ranging from approximately 60degrees to approximately 80 degrees. Preferably, the vertical boom tubeelement 2903 is folded at an angle of 70 degrees with respect to thehorizontal portion of the boom 2904. This design is advantageous overmany other designs as it takes less time to deploy and stow the boomsince the required travel distance of the vertical boom element isshortened by approximately 22%, which is critical to the dual-sidedoperation of the rotating boom elements as described above. In addition,limiting the travel of the swing for the vertical boom element reducesthe load and stress to the cable or hydraulic elements used to providethe deployment and stowing motion. When the vertical boom element is inthe preferable 70-degree stowed position, the overall center of gravityof the entire system is effectively lowered by reducing the weight inthe uppermost portions of its configuration. In addition, the 70-degreeposition of the vertical boom element allows for less encroachment intothe head room of the operator cabin.

Referring back to FIG. 29, the radiation source (not shown), which asmentioned above is located on a rotatable platform (also not shown) onthe connecting structure 2906 of the boom, and can be rotated from astorage position to a deployed position. Additionally, the detectorsarrays (not shown, but located on the both the horizontal portion of theboom 2904 and the vertical boom tube element 2903) are preferablyintegrally formed to allow for stable, yet rapid deployment. In oneembodiment, the detectors comprise three sections that are capable ofbeing folded, such that, when in a storage position, the detectorsrecess into the side of the inspection trailer. As mentioned above, byforming detectors such that they can fold into a storage position, it ispossible to produce a company trailer that can safely, and legally,travel roadways. When unfolded during operation, the detectors assumeeither a linear or an arched shape. In a linear arrangement, thedetectors are linear arrays that extend approximately 30 degrees to thebase of the trailer and, when deployed, extend substantially orthogonalto the base of the trailer.

Referring back to FIG. 27, in a preferred position, the detectors assumean approximate “C”-shape when unfolded. The preferred inverted“C”-shaped detector enables the radiation source to be closer to thetarget vehicle, thus allowing higher penetration capability, andprovides for complete scanning of the target OUI without corner cutoff.In addition, the preferred “C”-shape allows for a shorter total heightof detectors in folded position, minimizes alignment problems becausethe top and bottom sections are substantially co-linear, provides arelatively smaller radiation dose to all detectors, and are less proneto damage by the effective overall height of the trailer.

In order to facilitate push-button deployment and the dispensing away ofassembling tools or skill, the action folding or unfolding of thedetectors is enabled by a suitable hydraulic and or cable system knownto a person of ordinary skill in the art. Such exemplary hydraulicsystem has already been described above with respect to the firstembodiment of the present invention and will not be discussed in furtherdetail here.

The detector array as employed in the mobile scanning system of thepresent invention may be formed by a stack of crystals that generateanalog signals when X-rays impinge upon them, with the signal strengthproportional to the amount of beam attenuation in the OUI. In oneembodiment, the X-ray beam detector arrangement consists of a lineararray of solid-state detectors of the crystal-diode type. A typicalarrangement uses cadmium tungstate scintillating crystals to absorb theX-rays transmitted through the OUI and to convert the absorbed X-raysinto photons of visible light. Crystals such as bismuth germinate,sodium iodide or other suitable crystals may be alternatively used asknown to a person of ordinary skill in the art. The crystals can bedirectly coupled to a suitable detector, such as a photodiode orphoto-multiplier. The detector photodiodes could be linearly arranged,which through unity-gain devices, provide advantages overphoto-multipliers in terms of operating range, linearity anddetector-to-detector matching. In another embodiment, an area detectoris used as an alternative to linear array detectors. Such an areadetector could be a scintillating strip, such as cesium iodide or othermaterials known in the art, viewed by a suitable camera or opticallycoupled to a charge-coupled device (CCD).

At any point in time when the radiation source is on, the detectors aresnapshots of the radiation beam attenuation in the OUI for a particular“slice” of the OUI. Each slice is a beam density measurement, where thedensity depends upon beam attenuation through the OUI. The radiationdetectors convert the lateral radiation profile of the OUI intoelectrical signals that are processed in an image processing system,housed in the inspection trailer, while the OUI is being conducted pastthe source and the radiation detector.

The X-ray image processing and control system, in an exemplaryembodiment, comprises a computer and storage systems which record thedetector snapshots and software to merge them together to form an X-rayimage of the vehicle which may further be plotted on a screen or onother media. The X-ray image is viewed or automatically analyzed by OUIacquisition system such as a CRT or monitor that displays the X-rayimage of the vehicle to an operator/analyst. Alternatively, the OUIacquisition systems may be a database of X-ray images of desiredtargets, such as automobiles, bricks or other shapes that can becompared with features in the image. As a result of this imaging, onlyarticles that were not contained in the reference image of the containeror vehicle are selectively displayed to an operator/analyst. This makesit easier to locate articles that do not correspond to a referencecondition of the container or vehicle, and then to conduct a physicalinspection of those articles. Also, for high-resolution applications,the electronics used to read out the detector signals may typicallyfeature auto-zeroed, double-correlated sampling to achieve ultra-stablezero drift and low-offset-noise data acquisition. Automatic gain rangingmay be used to accommodate the wide attenuation ranges that can beencountered with large containers and vehicles.

FIG. 31 depicts an exemplary use of the self-contained inspection system3100 of the present invention, as it scans an object under inspection.In one preferred use of the system, the inspection trailer is driven tothe inspection site by a tug-vehicle 3101. After positioning theinspection trailer 3101, the radiation source 3102 is rotated onplatform 3103 of boom 3104 from a stowed/storage position into adeployed position. The relative position between the radiation sourceand detector are fixed to avoid distortion in images caused by themovement of scanner and/or detectors over uneven ground or due tounstable structures. Radiation source box 3102 is preferably placedlaterally opposite the detector array(s) 3105 at a distance that issuitable to allow an OUI to pass between the source and detector arrayduring the scanning process (the inspection aperture), yet on the sameplatform as the detection system to allow for a fixed relative positionthereby reducing the need for additional alignment. In addition, asmentioned above, this placement effectively counterbalances the weightof the detector boom, offsetting the weight and length of the detectorboom, reducing the overall weight and deployed width of the system. Theelectrical power generator, housed in the trailer, is turned on toprovide power to the electrical devices in the system.

While deploying the generator, the detector array 3105 is unfolded. Thedetector array 3105 may be positioned in a variety of ways, includinglinear or an approximate inverted “L” shape, and is unfolded using asuitable hydraulic or cable mechanism as described above. The trailer isstabilized due to the counterbalance weight of the radiation source 3102located on the same boom as the detector array 3105 but placed laterallyon the opposite side. Once the trailer is stable, the detector hydraulicor cable system is activated, causing the vertical detector section tounfold downwards. After unfolding the detector panel to a suitableposition, the detector panel is held into the required unfoldedposition. The detector panel is held into the required unfolded positionvia, but not limited to, use of a latch, gravity, or hydraulic pressure.

During the scanning operation, the radiation source 3102 and detectorarray 3105, both housed on the trailer, are activated and mobilized andpass over the OUI while the OUI remains stationary. In a preferredembodiment, during the scanning operation, the source and detectorsremain stationary and aligned with respect to each other while mobilizedand passed over the OUI. In a preferred embodiment, the motion of thescanner is kept steady and at a constant velocity. Since, irregularitiesin the motion of the vehicle may result in distortions in the scannedimage, the motion is preferably made as regular, even and constant asfeasible using known control systems such as by engaging the trailermotor in “auto speed” mode. As described in greater detail below, thescanning system is manipulated via a closed loop method to automaticallycorrect images for the different speeds of operation of the scanningtrailer. Such speed control system is a combination of mechanical,electrical, and software design.

In another embodiment, the relocatable inspection system remainsdeployed and stationary, while the OUI is propelled through the systemusing a conveyor type device. The vehicle under inspection istransported through the inspection aperture using a track-based carrierwhich pulls the vehicle forward using its front wheels.

In yet another embodiment, the relocatable inspection system employs arail-based carrier. In a rail-based system, the imaging elements,including the radiation source, the boom structure, the detector arrayand associated electronics are all mounted to a rail-based carrier. Theimaging elements are moved along the rails with an integrated drivesystem. Power for the system is supplied with, but not limited to,shore-based electrical power or an electrical generator. The image datais transferred to the imaging computers and corresponding display,housed in a separate control room.

A start mechanism may be employed and strategically placed so that whenthe beam area passes over the object under inspection, the radiationsource is activated to emit a substantially planar fan-shaped or conicalbeam (for the duration of the pass) that is suitably collimated forsharpness and made to irradiate substantially perpendicular to the pathof the vehicle.

Optionally, where the OUI is optionally driven underneath and throughthe self-contained inspection system, or if the self-containedinspection system is stationary as described above, start-sensors may bestrategically placed to allow an imaging and control system, locatedwithin the inspection trailer, to determine that the OUI cab and/or theload, in the case of a vehicle, has passed the area of the beam and thevehicle to be inspected is about to enter the X-ray beam position. Thus,as soon as the vehicle to be inspected trips the start-sensors, theradiation source is activated to emit a substantially planar fan-shapedor conical beam for the duration of the pass that is suitably collimatedfor sharpness and made to irradiate substantially perpendicular to thepath of the vehicle.

The post collimator 3107 is integrally connected between the radiationsource 3102 and the vertical boom tube 3108, providing for a moreprecise X-ray beam critical to reducing scattered X-ray and the X-raydose to the object being scanned. Since the source and detector remainin a relative stationary and fixed position during the scanning process,collimation can be adjusted to an advantageous minimum such that the fanbeam emerging out of the collimator just covers the detectors. Thecollimation mechanism is employed through the vertical boom tube 3108 ormay also be employed via any other suitable mechanism as is known to aperson of ordinary skill in the art.

Referring back to FIG. 21, a rotating collimation wheel of oneembodiment of the present invention is depicted. The collimator is usedto develop a pencil beam, which passes though the object. Across-section of the pencil beam is substantially rectangular, but notlimited to such configurations. The dimensions of pencil beam typicallydefine the scatter image resolution, which may be obtained with thesystem. Also, the fan angle of the fan beam is wide enough so that theradiation from the source completely covers the cross section of thevehicle from the side and the radiation is incident on the approximately“C”-shaped radiation detectors. The weight of the post collimation, inthis preferred embodiment, is favorable as it counterbalances a portionof the boom weight.

As known in the art, X-ray scanning operates on the principle that, asX-rays pass through objects, the radiation gets attenuated, absorbed,and/or deflected owing to a number of different physical phenomena thatare indicative of the nature of the material being scanned. Inparticular, scattering occurs when the original X-ray hits an object andis then deflected from its original path through an angle. These scatterradiations are non-directional and proportional to the total energydelivered in beam path. A narrowly collimated beam will keep the overallradiation dose minimal and therefore also reduce the amount of scatterradiation in the area surrounding the scanner, thereby reducing the“exclusion zone”, as mentioned above.

Because the trailer moves over the OUI, it does not need to bepositioned strategically to allow for high throughput. Rather, thetrailer may be driven over any OUI, located anywhere, given that thereis space for the inspection trailer to pass without disrupting portactivities. Another aspect that may influence the decision ofpositioning the trailer could be the availability of a large enougharea, called the “exclusion zone”, around the scanner system. Theexclusion zone is an area around the scanner in which the general publicis not authorized to enter due to the possibility of exposure to dosesof scattered or primary beam radiation during the scanning process. Theexclusion area is dependent upon the magnitude of current setting theintensity of the radiation source.

FIG. 32 is a schematic representation of the exemplary use of theself-contained inspection system of the present invention, scanning anobject under inspection, as shown in FIG. 31, detailing preferreddimensions of the scanning system of the present invention. The presentinvention generates a graphical representation, i.e., an image, of thedensities of the contents of the vehicle under inspection. This allowsfor easy visual interpretation of the results of the scanning of theOUI.

Advantageously, the preferred software system also causes the display ofa reference image simultaneously with the image generated in response tothe vehicle under inspection, so that an operator of the presentembodiment can easily make a visual comparison between what an object ofthe type being inspected should “look like”, and what the OUI actually“looks like”. Such “side-by-side” inspection further simplifies thedetection of contraband using the present embodiment. A suitablealgorithm or electronic hardware implements a correction that takes intoaccount the speed of the scanning trailer under motion, the scanningrate (i.e., number of lines scanned per second), detector size, anddistance between the detectors.

Referring back to FIG. 26, a flow chart depicts the operational steps ofthe mobile inspection system of the present invention once the imagegeneration program is executed. The details of such operational stepsonce image generation has been executed have already been described indetail above with respect to the second preferred embodiment and willnot be repeated here. Image processing techniques for the thirdpreferred embodiment of the present invention are preferably asdescribed with respect to FIG. 26 above.

The above examples are merely illustrative of the many applications ofthe system of present invention. Although only a few embodiments of thepresent invention have been described herein, it should be understoodthat the present invention might be embodied in many other specificforms without departing from the spirit or scope of the invention. Forexample, other configurations of cargo, tires, tankers, doors, airplane,packages, boxes, suitcases, cargo containers, automobile semi-trailers,tanker trucks, railroad cars, and other similar objects under inspectioncan also be considered. Therefore, the present examples and embodimentsare to be considered as illustrative and not restrictive, and theinvention is not to be limited to the details given herein, but may bemodified within the scope of the appended claims.

1. A system for inspecting a vehicle, having contraband, and generatingan image representation of said contraband, comprising: a radiationsource; a movable boom comprising at least a first and second portion,wherein the movable boom is adapted to be moved from a first position toa second position; a detector array comprising a plurality of detectorsand attached to one of the portions of the movable boom, wherein, uponmoving said boom to the second position, an inspection region is formedby the radiation source and the detector array; and a processing system,wherein said processing system is configured to Calibrate the pluralityof detectors by deriving a baseline radiation measurement, wherein saidbaseline radiation measurement is taken before said vehicle enters theinspection region; Irradiate said vehicle within said inspection region;Obtain measurements of transmitted radiation from said plurality ofdetectors; Generate an image from said measurements; and Display saidimage simultaneously with a reference image, wherein said referenceimage comprises a representation of a vehicle without contraband.
 2. Thesystem of claim 1 wherein said image has a resolution of grid pointsspaced approximately every 5 cm long the length and approximately 4.3 cmalong a height of the vehicle.
 3. The system of claim 1 wherein saidimage has a resolution adequate to achieve a detectability limit of lessthan 0.5 kilogram of contraband.
 4. The system of claim 1 wherein threebaseline radiation measurements are obtained for each detector in saiddetector array.
 5. The system of claim 1 wherein each of said baselineradiation measurements are stored in an array in a memory.
 6. The systemof claim 1 wherein the first portion is vertical and physically attachedto a platform, wherein the detector array is physically attached to thesecond portion of said movable boom, and wherein the radiation source islocated on said platform.
 7. The system of claim 1 wherein the firstportion is vertical and physically attached to a platform and whereinthe detector array is physically attached to the first portion of saidmovable boom.
 8. The system of claim 1 wherein the measurements oftransmitted radiation from said plurality of detectors are indicative ofphoto current levels.
 9. The system of claim 1 wherein the measurementsof transmitted radiation from said plurality of detectors are obtainedby querying each detector for a photo current level measurement.
 10. Thesystem of claim 1 wherein the processing system obtains photo currentlevel measurements, stores said current level measurements in an array,and converts said stored photo current level measurements into pixelvalues.
 11. The system of claim 10 wherein the stored photo currentlevel measurements are converted into pixel values by mapping an amountof photo current level to a color.
 12. The system of claim 1 wherein theprocessing system determines a vertical display position of each pixelvalue and wherein said vertical display position is determined basedupon a number of the detector that generated a photo current levelmeasurement which was converted to said pixel value.
 13. The system ofclaim 1 wherein the processing system determines a horizontal displayposition of each pixel value and wherein said horizontal displayposition is determined based upon an horizontal position associated witha photo current level measurement which was converted to said pixelvalue.
 14. A system for inspecting a vehicle, having contraband, andgenerating an image representation of said contraband, comprising: aradiation source; a movable boom comprising at least a first and secondportion, wherein the movable boom is adapted to be moved from a firstposition to a second position; a detector array comprising a pluralityof detectors and attached to one of the portions of the movable boom,wherein, upon moving said boom to the second position, an inspectionregion is formed by the radiation source and the detector array; and aprocessing system, wherein said processing system is configured toCalibrate the plurality of detectors by deriving a baseline radiationmeasurement, wherein said baseline radiation measurement is taken beforesaid vehicle enters the inspection region; Irradiate said vehicle withinsaid inspection region; Obtain measurements of transmitted radiationfrom said plurality of detectors; Generate an image from saidmeasurements, said image comprising a plurality of pixels defining animage resolution; and Display said image, wherein said image resolutionis sufficient to detect less than 0.5 kilograms of contraband per pixel.15. The system of claim 14 wherein the processing system obtains threebaseline radiation measurements for each detector in said detectorarray.
 16. The system of claim 14 wherein the first portion is verticaland physically attached to a platform, wherein the detector array isphysically attached to the second portion of said movable boom.
 17. Thesystem of claim 16 wherein the radiation source is located on saidplatform.
 18. The system of claim 14 wherein the first portion isvertical and physically attached to a platform and wherein the detectorarray is physically attached to the first portion of said movable boom.19. The system of claim 14 wherein the measurements of transmittedradiation from said plurality of detectors are indicative of photocurrent levels.
 20. The system of claim 14 wherein the measurements oftransmitted radiation from said plurality of detectors are obtained byquerying each detector for a photo current level measurement.